Alkaline positions in CsTiOAsO₄

The caesium titanyl arsenate structure has been studied to determine the status of the cation sites. At room temperature, residual charge density was accumulated at a distance of approximately 0.7 Å from the Cs sites. This could be attributed to partial occupancy of additional sites related by pseudo-symmetry. The occupancies of the split Cs positions were about 0.8 for the original site and 0.2 for the additional Cs position. The additional Cs positions were displaced from the two original sites along the polar c axis at distances of 0.366 (8) and 0.26 (2) Å, respectively.

S1. Comment

Caesium titanyl arsenate, CTA, belongs to the KTiOPO₄ (KTP) isomorphic family of compounds, known for their excellent ferroelectric and non-linear optical properties (Stucky et al., 1989). Arsenates such as RbTiOAsO₄ (RTA) and CTA have high transmission in the IR region, superior to that of KTP, and this property can be used to extend the optical range of lasers (Mangin et al., 1989).

The general structure in CTA is a three-dimensional network of AsO₄ tetrahedra and distorted TiO₆ octahedra, with periodic bond chains of –AsO₄—TiO₆—AsO₄—TiO₆ along the a and b directions and the ac diagonal (Protas et al., 1989). In the octahedra, the Ti atoms are displaced, giving alternating shorter (Ti1—O12 and Ti2—O11) and longer (Ti2—O12 and Ti1—O11) bonds along the polar c axis. The three-dimensional network has open channels along c, with two different sites for the Cs cations. The ferroelectric phase transition for KTP isomorphs is continuous second order of both displacive and order-disorder type (Belokoneva et al., 1997). During the transformation from the paraelectric to the ferroelectric phase, the cations are displaced along the polarization vector to two independent sites. However, elements of the high temperature structure are retained at room temperature (Thomas et al., 1990; Thomas & Womersley, 1998).

Womersley et al. (1998) have reported some evidence of disorder of the cations over additional sites along the c direction for Cs-rich compounds of Cs_xRb_{1 - x}TiOAsO₄ mixtures. Split alkaline positions had previously been refined for KFeFPO₄ at room temperature (Belokoneva et al., 1990). The KTP and RbTiOPO₄ (RTP) structures have been studied at elevated temperatures by Delarue et al. (1998, 1999). The split cation sites model could be applied at temperatures higher than 473 K. For RTA, additional density at the Rb sites was noted in the 9.6 K structure but refinement of the split positions model was not applicable (Almgren et al., 1999). Recently, synchrotron data at room temperature by Streltsov et al. (2000) has shown that a combination of split Rb positions and multipole functions in the refinement gives the best description of the RTA structure. The question has been posed as to whether the split alkaline positions are universal for KTP isomorphs. Thus, it was desirable to conduct an accurate X-ray diffraction study of the CTA structure to investigate the status of the Cs positions and how these would change with temperature.

Flack parameter refinements (see below) indicated that a single-domain crystal was used. Model I, with two fully occupied Cs sites, was first refined for the room temperature structure. It resulted in significant residual electron density found along the c direction at both Cs sites at a distance of approximately 0.67 and 0.75 Å from Cs1 and Cs2, respectively. The use of Model II, with split Cs positions, resulted in a better fit of the refined structure to experimental data and significantly reduced the excess electron density around the Cs atoms. The refined positions were found closer to the original Cs positions than the additional density resulting from the Model I refinement. The new Cs3 atom was positioned 0.366 (8) Å from Cs1 along the c axis. For the Cs2—Cs4 couple, the corresponding distance was 0.26 (2) Å. This could be compared with the interatomic distances in the a and b directions, which were an order of magnitude shorter. The occupancies of the split Cs positions were 0.800 (7) for Cs1 and 0.200 (7) for Cs3, and 0.80 (1) for Cs2 and 0.20 (1) for Cs4. This could be compared with the RTA room temperature structure, where the Rb1 site has an occupancy of 0.885 (5) and Rb2 an occupancy of 0.872 (9). The shifts of the additional Rb positions are 0.303 (2) and 0.228 (3) Å for the Rb1—Rb3 and Rb2—Rb4 pairs, respectively (Streltsov et al., 2000). In RTP at 473 K the corresponding distances are 0.27 (1) and 0.19 (1) Å. It could therefore be concluded that the splitting is more pronounced in CTA than in the KTP isomorphs previously re-investigated.

An ORTEP plot (Johnson et al., 1972) of the room temperature structure in the ac plane is given in Fig. 1. The elongated isotropic displacement ellipsoid of Cs4 indicates that this additional site is in fact not one position but represents several Cs positions which cannot be resolved. The isotropic displacement parameters along the principal axes have been calculated using the program ORFFE modified for PC (Busing et al., 1964; Gustafsson, 1993). For Cs4, the isotropic displacements along the principal axes r₁, r₂ and r₃ were 0.06 (3), 0.13 (1) and 0.24?(1) Å, respectively. The corresponding values for Cs2 were 0.093 (3), 0.107 (3) and 0.155 (3) Å, respectively. The r.m.s. parameters were more uniform for the Cs1—Cs3 pair, with displacements along r₁ and r₃ of 0.095 (1) and 0.172 (2), respectively, for Cs1, and 0.085 (9) and 0.17 (1) Å, respectively, for Cs3. The Cs1 and Cs2 atoms vibrate predominately in the [001] direction with an angle to the c axis of 25 (5)°. Atoms Cs3 and Cs4 also vibrate mainly in this direction. This is correlated with the coordination of the Cs sites situated in the channels along c and with no oxygen bonds in the [001] direction.

At 183 K, the residual electron density near the Cs atoms could not be resolved to any specific split positions and for this temperature Model I was used in the refinement. The atomic coordinates for Cs1 and Cs2 were very similar to the coordinates for the same atoms at room temperature. This indicates that the additional Cs peaks have moved towards the dominant Cs sites. It should be noted that in the refinement of the room temperature structure using Model I, the fractional z coordinates of Cs1 and Cs2 were in between those of the Cs1—Cs3 and Cs2—Cs4 pairs in Model II. For the RTA structure on the other hand, the average z coordinates at room temperature of Rb1—Rb3 and Rb2—Rb4, respectively (Streltsov et al., 2000), corresponded well with the 9.6 K coordinates of Rb1 and Rb2 (Almgren et al., 1999). The thermal displacements along the principal axes r₁, r₂ and r₃ were 0.073 (2), 0.100 (1) and 0.150 (1) Å, respectively, for Cs1, and 0.072 (2), 0.091 (1) and 0.1255 (8) Å, respectively, for Cs2, at 183 K. Both cations vibrated in the [001] direction with an angle of 18 (1)° to the c axis.

The original Cs sites are coordinated by nine O atoms and this is also true for the additional Cs4 site. Cs3 is, on the other hand, coordinated by six O atoms; selected atomic bond distances are given in Table 1. The three-dimensional network structure was little affected by the inclusion of additional Cs positions at room temperature. No significant differences were noted in the bond lengths, neither in the Ti octahedra nor in the As tetrahedra. As the Cs1 and Cs2 sites at room temperature correspond to those at 183 K, the Cs1—O and Cs2—O bonds did not change significantly with temperature (Table 2).

S2. Experimental

CTA crystals were made from spontaneous growth using a self-flux of Cs₅As₃O₁₀, with 0.6 g C T A per 1 g flux, made from analytical grade Cs₂CO₃, As₂O₅ and TiO₂ (Cheng et al., 1993). The powder starting materials were mixed thoroughly using an agate mortar and placed in a pure Pt crucible. This was inserted into a vertical tube furnace, which was quickly heated to 470 K where it was kept for 12 h to allow for dehydration of the hygroscopic powders. Then the flux was slowly heated to 1230 K where it was maintained for 24 h as the flux melt was homogenized by stirring with a Pt spoon. Growth was accomplished by cooling from 1085 to 1066 K by 2 K per day, after which the flux containing crystals was cooled to room temperature at a rate of 200 K per day. Small clear crystals were recovered by dissolution in water; some crystals had a slightly yellow colour. Many of the smaller crystals had needle-like morphology, which has previously been observed in supercooled melts of CTA (Cheng et al., 1993), while some of the larger crystals had typical KTP morphology (Bolt & Bennema, 1990). However, none of the crystals were small enough to reduce the extinction effect on the X-ray diffraction data efficiently. Therefore, the sample chosen for the present crystallographic study was cut from a small clear crystal of needle-like morphology.

S3. Refinement

Full-matrix least-squares refinements were made using the independent atom model. The Zachariasen extinction parameter r* was refined in accordance with the Larson implementation (Larson, 1969). The minimum extinction correction parameter y_min was 0.85 (Model I) and 0.83 (Model II) at 297 K, and 0.88 at 183 K for the 013 reflection (the observed structure factor is F_obs = yF_kin, where F_kin is the kinematical value of the structure factor). The refined Flack (1983) parameter of 0.05 (2) at 297 K and 0.06 (2) at 183 K shows that the crystal is nearly single-domain. The Flack parameter refinement was made using 2188 Friedel pairs at 297 K and 2553 Friedel pairs at 183 K. For the 183 K data, the anisotropic thermal displacement parameters for O8 and O12 showed odd values and isotropic parameters were used in the final refinements.

Computing details

For all compounds, data collection: SMART (Siemens, 1995); cell refinement: SAINT (Siemens, 1995); data reduction: SAINT and SADABS (Sheldrick, 1996); program(s) used to refine structure: Xtal (Hall et al., 1999); molecular graphics: Xtal; software used to prepare material for publication: Xtal.

Figures

Fig. 1. An ORTEP plot (Johnson et al., 1972) of the room temperature CTA structure in the plane perpendicular to the b axis. Split alkaline positions are shown by the Cs1—Cs3 and Cs2—Cs4 pairs and all atoms are given as 99% probability level displacement ellipsoids. The elongated ellipsoid of Cs4 indicates that this additional site comprises several positions that cannot be individually resolved [symmetry codes: (ii) 3/2 - x, y - 1/2, z - 1/2; (iv) 1/2 + x, 3/2 - y, z; (vii) 1 - x, 1 - y, z - 1/2; (viii) 3/2 - x, 1/2 + y, z - 1/2].

(I)

Crystal data

CsTiOAsO4	F(000) = 1200
Mr = 335.7	Dx = 4.505 Mg m^−3
Orthorhombic, Pna21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2c -2n	Cell parameters from 6935 reflections
a = 13.4892 (3) Å	θ = 3.0–41.8°
b = 6.8637 (1) Å	µ = 15.54 mm^−1
c = 10.6908 (1) Å	T = 297 K
V = 989.82 (3) Å^3	Rectangular, colourless
Z = 8	0.03 × 0.02 × 0.02 mm

Data collection

Siemens SMART CCD diffractometer	6720 independent reflections
Radiation source: fine-focus sealed tube	4208 reflections with F^2 > 3σ(F^2)
Graphite monochromator	Rint = 0.078
ω scans	θmax = 41.8°, θmin = 3.0°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −25→25
Tmin = 0.65, Tmax = 0.75	k = −12→12
36263 measured reflections	l = −19→19

Refinement

Refinement on F	1/σ^2
Least-squares matrix: full	(Δ/σ)max = 0.001
R[F^2 > 2σ(F^2)] = 0.038	Δρmax = 3.14 e Å^−3
wR(F^2) = 0.026	Δρmin = −2.39 e Å^−3
S = 1.89	Extinction correction: Zachariasen (1968), Eq22 p292 "Cryst. Comp." Munksgaard 1970
4208 reflections	Extinction coefficient: 617 (30)
146 parameters	Absolute structure: Flack (1983)
0 restraints	Absolute structure parameter: 0.05 (2)
0 constraints

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Cs1	0.61340 (5)	0.21408 (7)	0.38048 (11)	0.0241 (3)
Cs2	0.88947 (4)	0.30172 (7)	0.12288 (11)	0.0188 (3)
Ti1	0.62766 (7)	0.4971 (2)	0.02562 (16)	0.0065 (5)
Ti2	0.74831 (12)	0.7350 (2)	0.27700 (16)	0.0060 (5)
As1	0.49891 (7)	0.67401 (8)	0.28192 (12)	0.0052 (2)
As2	0.82237 (5)	0.49889 (12)	0.53624 (12)	0.0058 (2)
O1	0.5147 (6)	0.5256 (10)	0.1602 (5)	0.014 (3)
O2	0.4848 (5)	0.5392 (10)	0.4114 (5)	0.012 (3)
O3	0.6023 (4)	0.8076 (8)	0.3072 (5)	0.010 (3)
O4	0.3980 (5)	0.8160 (7)	0.2620 (5)	0.010 (3)
O11	0.7159 (5)	0.5588 (9)	0.1661 (5)	0.011 (3)
O12	0.7829 (5)	0.9428 (8)	0.4170 (5)	0.009 (3)
O5	0.8893 (5)	0.6986 (8)	0.5730 (5)	0.013 (3)
O6	0.8893 (5)	0.2992 (7)	0.4986 (5)	0.014 (3)
O7	0.7469 (5)	0.4524 (8)	0.6596 (5)	0.011 (3)
O8	0.7442 (5)	0.5510 (9)	0.4177 (15)	0.013 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cs1	0.0162 (3)	0.0092 (2)	0.0468 (4)	0.00267 (18)	−0.0058 (3)	−0.0044 (2)
Cs2	0.0114 (3)	0.0125 (2)	0.0326 (3)	0.00286 (18)	−0.0023 (2)	−0.0046 (2)
Ti1	0.0058 (4)	0.0080 (4)	0.0058 (5)	0.0009 (6)	0.0002 (4)	−0.0005 (5)
Ti2	0.0056 (4)	0.0067 (4)	0.0056 (5)	−0.0012 (4)	−0.0001 (5)	0.0007 (5)
As1	0.0047 (2)	0.0057 (2)	0.0054 (3)	−0.0002 (3)	0.0009 (3)	−0.0003 (2)
As2	0.0067 (2)	0.0054 (2)	0.0053 (3)	0.0001 (3)	−0.0000 (3)	0.0005 (2)
O1	0.015 (4)	0.013 (3)	0.014 (3)	−0.005 (2)	0.005 (2)	−0.006 (2)
O2	0.007 (3)	0.017 (3)	0.013 (3)	0.005 (2)	0.002 (2)	0.0060 (19)
O3	0.006 (3)	0.014 (2)	0.010 (3)	−0.002 (2)	−0.000 (2)	−0.002 (2)
O4	0.007 (3)	0.006 (2)	0.019 (3)	0.0009 (19)	−0.003 (2)	0.0003 (19)
O11	0.012 (3)	0.011 (2)	0.009 (3)	0.001 (2)	−0.001 (2)	−0.0016 (18)
O12	0.006 (3)	0.011 (2)	0.010 (3)	−0.001 (2)	−0.0012 (18)	−0.0032 (18)
O5	0.016 (3)	0.007 (2)	0.015 (3)	−0.003 (2)	−0.006 (2)	0.0011 (18)
O6	0.011 (3)	0.006 (2)	0.024 (3)	0.001 (2)	0.006 (2)	0.001 (2)
O7	0.009 (3)	0.011 (3)	0.012 (3)	0.003 (2)	−0.001 (2)	0.0021 (18)
O8	0.019 (4)	0.013 (3)	0.009 (3)	−0.008 (3)	−0.007 (2)	0.0050 (18)

Geometric parameters (Å, º)

Cs1—Cs2	3.8378 (12)	Ti1—O5	2.123 (5)
Cs1—O1	3.448 (6)	Ti1—O2	1.963 (6)
Cs1—O2	2.846 (7)	Ti1—O6	2.106 (5)
Cs1—O3	2.902 (5)	Ti1—O11	1.962 (6)
Cs1—O12	2.974 (6)	Ti1—O12	1.716 (6)
Cs1—O5	3.289 (5)	Ti2—O3	2.057 (6)
Cs1—O6	3.278 (6)	Ti2—O12	2.119 (6)
Cs1—O8	2.936 (7)	Ti2—O8	1.964 (13)
Cs1—Cs2	4.0890 (13)	Ti2—O4^i	2.055 (6)
Cs2—O3	3.377 (5)	Ti2—O11	1.749 (6)
Cs2—O4	3.018 (5)	Ti2—O7	1.951 (6)
Cs2—O11	2.968 (7)	As1—O1	1.666 (6)
Cs2—O12	3.345 (6)	As1—O2	1.676 (6)
Cs2—O7	3.048 (6)	As1—O3	1.691 (6)
Cs2—O2	3.351 (6)	As1—O4	1.688 (6)
Cs2—O8	3.321 (12)	As2—O5	1.687 (6)
Cs2—O1	2.839 (7)	As2—O6	1.690 (6)
Cs2—O5	3.032 (7)	As2—O8	1.687 (13)
Ti1—O1	2.105 (7)	As2—O7	1.696 (6)
O1—Cs1—O2	50.05 (15)	O3—Ti2—O4^i	173.7 (2)
O1—Cs1—O3	113.07 (15)	O3—Ti2—O11	92.0 (3)
O1—Cs1—O12	140.77 (16)	O3—Ti2—O7	87.0 (2)
O1—Cs1—O5	48.19 (14)	O12—Ti2—O8	84.2 (4)
O1—Cs1—O6	85.66 (16)	O12—Ti2—O4^i	87.3 (2)
O1—Cs1—O8	80.6 (3)	O12—Ti2—O11	177.4 (3)
O2—Cs1—O3	138.93 (18)	O12—Ti2—O7	86.1 (2)
O2—Cs1—O12	160.77 (17)	O8—Ti2—O4^i	88.7 (3)
O2—Cs1—O5	97.76 (15)	O8—Ti2—O11	93.9 (4)
O2—Cs1—O6	54.19 (16)	O8—Ti2—O7	170.1 (4)
O2—Cs1—O8	74.5 (2)	O4^i—Ti2—O11	94.3 (3)
O3—Cs1—O12	58.21 (16)	O4^i—Ti2—O7	92.7 (2)
O3—Cs1—O5	72.45 (14)	O11—Ti2—O7	95.8 (3)
O3—Cs1—O6	91.69 (14)	O1—As1—O2	108.8 (3)
O3—Cs1—O8	145.6 (2)	O1—As1—O3	110.6 (3)
O12—Cs1—O5	96.84 (15)	O1—As1—O4	111.0 (3)
O12—Cs1—O6	129.86 (15)	O2—As1—O3	105.1 (3)
O12—Cs1—O8	90.77 (18)	O2—As1—O4	109.4 (3)
O5—Cs1—O6	111.98 (16)	O3—As1—O4	111.9 (3)
O5—Cs1—O8	99.6 (3)	O5—As2—O6	115.4 (3)
O6—Cs1—O8	121.6 (2)	O5—As2—O8	109.7 (3)
O3—Cs2—O4	118.74 (13)	O5—As2—O7	107.0 (3)
O3—Cs2—O11	100.04 (14)	O6—As2—O8	109.1 (4)
O3—Cs2—O12	50.33 (14)	O6—As2—O7	110.7 (3)
O3—Cs2—O7	99.08 (13)	O8—As2—O7	104.4 (4)
O3—Cs2—O2	46.82 (14)	Cs1—O1—Ti1	97.4 (2)
O3—Cs2—O8	50.5 (2)	Cs1—O1—As1	84.0 (2)
O3—Cs2—O1	97.48 (14)	Cs1—O1—Cs2	80.51 (15)
O3—Cs2—O5	77.98 (14)	Ti1—O1—As1	133.1 (4)
O4—Cs2—O11	55.70 (17)	Ti1—O1—Cs2	105.1 (2)
O4—Cs2—O12	95.69 (15)	As1—O1—Cs2	121.2 (3)
O4—Cs2—O7	130.06 (16)	Cs1—O2—As1	105.5 (3)
O4—Cs2—O2	141.31 (16)	Cs1—O2—Cs2	101.1 (2)
O4—Cs2—O8	142.81 (16)	Cs1—O2—Ti1	116.4 (3)
O4—Cs2—O1	126.59 (17)	As1—O2—Cs2	101.7 (3)
O4—Cs2—O5	92.86 (16)	As1—O2—Ti1	132.2 (4)
O11—Cs2—O12	51.83 (14)	Cs2—O2—Ti1	92.3 (2)
O11—Cs2—O7	88.37 (17)	Cs1—O3—Cs2	74.93 (12)
O11—Cs2—O2	145.46 (15)	Cs1—O3—Ti2	103.1 (2)
O11—Cs2—O8	88.99 (17)	Cs1—O3—As1	127.4 (3)
O11—Cs2—O1	156.64 (17)	Cs2—O3—Ti2	97.0 (2)
O11—Cs2—O5	143.54 (16)	Cs2—O3—As1	100.4 (2)
O12—Cs2—O7	83.85 (15)	Ti2—O3—As1	129.3 (3)
O12—Cs2—O2	93.63 (14)	Cs2—O4—As1	126.5 (3)
O12—Cs2—O8	48.52 (16)	Cs2—O4—Ti2	98.6 (2)
O12—Cs2—O1	137.31 (16)	As1—O4—Ti2	133.2 (3)
O12—Cs2—O5	124.65 (15)	Cs2—O11—Ti1	103.4 (2)
O7—Cs2—O2	88.24 (16)	Cs2—O11—Ti2	108.6 (3)
O7—Cs2—O8	49.4 (2)	Ti1—O11—Ti2	145.1 (4)
O7—Cs2—O1	73.65 (19)	Cs1—O12—Cs2	74.54 (14)
O7—Cs2—O5	128.05 (15)	Cs1—O12—Ti2	99.2 (2)
O2—Cs2—O8	63.3 (2)	Cs1—O12—Ti1	119.6 (3)
O2—Cs2—O1	50.82 (15)	Cs2—O12—Ti2	96.7 (2)
O2—Cs2—O5	51.90 (15)	Cs2—O12—Ti1	96.1 (2)
O8—Cs2—O1	90.34 (17)	Ti2—O12—Ti1	141.1 (4)
O8—Cs2—O5	114.7 (2)	Cs1—O5—Ti1	101.9 (2)
O1—Cs2—O5	55.84 (18)	Cs1—O5—As2	104.7 (2)
O1—Ti1—O5	81.3 (2)	Cs1—O5—Cs2	80.50 (14)
O1—Ti1—O2	82.9 (3)	Ti1—O5—As2	132.1 (3)
O1—Ti1—O6	85.6 (3)	Ti1—O5—Cs2	98.5 (2)
O1—Ti1—O11	84.0 (3)	As2—O5—Cs2	124.5 (3)
O1—Ti1—O12	172.8 (3)	Cs1—O6—As2	127.4 (3)
O5—Ti1—O2	86.7 (3)	Cs1—O6—Ti1	97.2 (2)
O5—Ti1—O6	166.2 (3)	As2—O6—Ti1	135.1 (4)
O5—Ti1—O11	95.2 (2)	Cs2—O7—Ti2	134.8 (3)
O5—Ti1—O12	91.6 (3)	Cs2—O7—As2	96.6 (2)
O2—Ti1—O6	87.5 (3)	Ti2—O7—As2	128.6 (4)
O2—Ti1—O11	166.4 (3)	Cs1—O8—Cs2	99.9 (3)
O2—Ti1—O12	95.5 (3)	Cs1—O8—Ti2	114.8 (6)
O6—Ti1—O11	87.6 (2)	Cs1—O8—As2	108.1 (4)
O6—Ti1—O12	101.4 (3)	Cs2—O8—Ti2	100.8 (2)
O11—Ti1—O12	97.9 (3)	Cs2—O8—As2	87.3 (6)
O3—Ti2—O12	86.4 (2)	Ti2—O8—As2	134.0 (4)
O3—Ti2—O8	90.5 (3)

Symmetry code: (i) x+1/2, −y+1/2, z.

(II)

Crystal data

CsTiOAsO4	F(000) = 1200
Mr = 335.7	Dx = 4.505 Mg m^−3
Orthorhombic, Pna21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2c -2n	Cell parameters from 6935 reflections
a = 13.4892 (3) Å	θ = 3.0–41.8°
b = 6.8637 (1) Å	µ = 15.54 mm^−1
c = 10.6908 (1) Å	T = 297 K
V = 989.82 (3) Å^3	Rectangular, colourless
Z = 8	0.03 × 0.02 × 0.02 mm

Data collection

Siemens SMART CCD diffractometer	6720 independent reflections
Radiation source: fine-focus sealed tube	4208 reflections with F^2 > 3σ(F^2)
Graphite monochromator	Rint = 0.078
ω scans	θmax = 41.8°, θmin = 3.0°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −25→25
Tmin = 0.65, Tmax = 0.75	k = −12→12
36263 measured reflections	l = −19→19

Refinement

Refinement on F	1/σ^2
Least-squares matrix: full	(Δ/σ)max = 0.001
R[F^2 > 2σ(F^2)] = 0.034	Δρmax = 1.41 e Å^−3
wR(F^2) = 0.023	Δρmin = −1.26 e Å^−3
S = 1.73	Extinction correction: Zachariasen (1968), Eq22 p292 "Cryst. Comp." Munksgaard 1970
4208 reflections	Extinction coefficient: 712 (29)
164 parameters	Absolute structure: Flack (1983)
0 restraints	Absolute structure parameter: 0.05 (2)
0 constraints

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
Cs1	0.6139 (3)	0.2148 (5)	0.3757 (2)	0.0179 (6)	.800
Cs2	0.8892 (3)	0.3002 (5)	0.1198 (5)	0.0145 (7)	.79600
Ti1	0.62763 (6)	0.4970 (2)	0.02607 (17)	0.0068 (4)
Ti2	0.74834 (11)	0.73465 (17)	0.27740 (17)	0.0059 (4)
As1	0.49890 (6)	0.67407 (7)	0.28238 (14)	0.0055 (2)
As2	0.82235 (4)	0.49891 (11)	0.53681 (13)	0.0061 (2)
O1	0.5145 (5)	0.5257 (9)	0.1611 (4)	0.014 (3)
O2	0.4848 (5)	0.5387 (9)	0.4121 (4)	0.012 (3)
O3	0.6022 (4)	0.8074 (7)	0.3077 (4)	0.010 (2)
O4	0.3978 (4)	0.8158 (6)	0.2616 (4)	0.011 (2)
O11	0.7161 (5)	0.5583 (8)	0.1669 (5)	0.012 (3)
O12	0.7829 (4)	0.9422 (7)	0.4176 (4)	0.009 (2)
O5	0.8887 (4)	0.6994 (7)	0.5735 (4)	0.011 (2)
O6	0.8897 (4)	0.3001 (7)	0.4998 (5)	0.012 (2)
O7	0.7470 (4)	0.4527 (7)	0.6603 (4)	0.011 (3)
O8	0.7440 (5)	0.5510 (8)	0.4180 (4)	0.014 (3)
Cs3	0.6109 (11)	0.2099 (18)	0.4096 (7)	0.017 (2)	.200
Cs4	0.8901 (12)	0.306 (2)	0.1437 (17)	0.025 (4)	.204

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cs1	0.0163 (5)	0.0096 (3)	0.0278 (10)	0.0028 (3)	−0.0039 (8)	−0.0027 (7)
Cs2	0.0098 (5)	0.0118 (6)	0.0220 (10)	0.0021 (4)	−0.0019 (5)	−0.0046 (6)
Ti1	0.0060 (4)	0.0082 (4)	0.0063 (5)	0.0009 (5)	0.0005 (4)	−0.0009 (4)
Ti2	0.0058 (4)	0.0065 (4)	0.0056 (5)	−0.0011 (3)	−0.0003 (4)	0.0007 (4)
As1	0.0049 (2)	0.00591 (19)	0.0059 (2)	−0.0001 (3)	0.0010 (2)	−0.0002 (2)
As2	0.0070 (2)	0.00561 (19)	0.0057 (2)	0.0002 (3)	−0.0001 (3)	0.0005 (2)
O1	0.014 (3)	0.014 (2)	0.014 (3)	−0.005 (2)	0.0053 (18)	−0.0059 (17)
O2	0.008 (3)	0.016 (2)	0.013 (3)	0.005 (2)	0.0022 (17)	0.0059 (17)
O3	0.005 (2)	0.013 (2)	0.011 (2)	−0.0012 (18)	0.0002 (17)	−0.0035 (17)
O4	0.009 (2)	0.0077 (18)	0.015 (3)	0.0013 (17)	−0.0017 (18)	0.0003 (17)
O11	0.012 (3)	0.012 (2)	0.010 (2)	0.0022 (18)	−0.0002 (19)	−0.0020 (17)
O12	0.007 (3)	0.010 (2)	0.009 (2)	−0.0016 (17)	−0.0025 (16)	−0.0017 (15)
O5	0.015 (2)	0.0069 (18)	0.011 (2)	−0.003 (2)	−0.003 (2)	0.0013 (16)
O6	0.012 (2)	0.0080 (18)	0.016 (3)	0.001 (2)	0.006 (2)	−0.0002 (17)
O7	0.011 (3)	0.012 (2)	0.009 (3)	0.003 (2)	−0.0011 (18)	0.0017 (16)
O8	0.018 (3)	0.013 (2)	0.010 (3)	−0.008 (2)	−0.005 (2)	0.0056 (16)
Cs3	0.0152 (16)	0.0084 (14)	0.028 (4)	0.0015 (13)	−0.001 (3)	−0.004 (3)
Cs4	0.021 (2)	0.0145 (19)	0.041 (7)	0.0071 (16)	−0.010 (3)	−0.019 (3)

Geometric parameters (Å, º)

Cs1—O1	3.408 (6)	Cs4—O7	3.057 (17)
Cs1—O2	2.851 (7)	Cs4—O2	3.515 (17)
Cs1—O3	2.893 (6)	Cs4—O8	3.49 (2)
Cs1—O11	3.528 (6)	Cs4—O3	3.594 (17)
Cs1—O12	2.983 (7)	Cs4—O12	3.486 (17)
Cs1—O5	3.233 (5)	Cs4—O1^i	2.837 (17)
Cs1—O6	3.303 (7)	Cs4—O5	3.076 (17)
Cs1—O7	3.473 (6)	Ti1—O1	2.109 (6)
Cs1—O8	2.934 (7)	Ti1—O11	1.967 (6)
Cs1—Cs3	0.366 (8)	Ti1—O5	2.116 (5)
Cs2—O4	3.043 (6)	Ti1—O2	1.960 (6)
Cs2—O11	2.974 (7)	Ti1—O6	2.112 (5)
Cs2—O7	3.041 (6)	Ti1—O12	1.716 (5)
Cs2—O2	3.323 (7)	Ti2—O4	2.052 (6)
Cs2—O8	3.287 (7)	Ti2—O11	1.747 (5)
Cs2—O3	3.339 (7)	Ti2—O8	1.962 (18)
Cs2—O12	3.318 (7)	Ti2—O3	2.059 (5)
Cs2—O1^i	2.838 (7)	Ti2—O12	2.120 (5)
Cs2—O5	3.036 (7)	Ti2—O7	1.952 (5)
Cs2—Cs4	0.260 (18)	As1—O1	1.663 (5)
Cs3—O2	2.826 (15)	As1—O2	1.681 (5)
Cs3—O3	2.972 (13)	As1—O3	1.689 (5)
Cs3—O12	2.961 (15)	As1—O4	1.690 (5)
Cs3—O5	3.594 (9)	As2—O5	1.688 (5)
Cs3—O6	3.136 (15)	As2—O7	1.696 (5)
Cs3—O8	2.952 (15)	As2—O6	1.686 (5)
Cs4—O4	2.885 (16)	As2—O8	1.691 (5)
Cs4—O11	2.926 (17)
O1—Cs1—O2	50.47 (14)	Cs3—O3—Cs2	69.3 (2)
O1—Cs1—O3	114.47 (16)	Cs3—O3—Cs4	68.5 (3)
O1—Cs1—O11	46.30 (15)	As1—O3—Cs2	100.4 (2)
O1—Cs1—O12	142.58 (17)	As1—O3—Cs4	100.5 (3)
O1—Cs1—O5	48.94 (13)	Cs2—O3—Cs4	0.8 (2)
O1—Cs1—O6	85.98 (16)	Cs2—O4—Cs4	4.0 (4)
O1—Cs1—O7	95.17 (14)	Cs2—O4—Ti2	98.6 (2)
O1—Cs1—O8	81.16 (16)	Cs2—O4—As1	126.5 (3)
O2—Cs1—O3	139.0 (2)	Cs4—O4—Ti2	98.8 (4)
O2—Cs1—O11	78.70 (16)	Cs4—O4—As1	127.1 (4)
O2—Cs1—O12	159.31 (18)	Ti2—O4—As1	133.2 (3)
O2—Cs1—O5	98.92 (16)	Cs1—O11—Cs2	90.92 (17)
O2—Cs1—O6	53.85 (16)	Cs1—O11—Ti1	96.0 (2)
O2—Cs1—O7	145.54 (16)	Cs1—O11—Cs4	88.4 (4)
O2—Cs1—O8	74.40 (19)	Cs1—O11—Ti2	97.6 (2)
O3—Cs1—O11	120.52 (16)	Cs2—O11—Ti1	102.7 (2)
O3—Cs1—O12	58.22 (16)	Cs2—O11—Cs4	5.0 (4)
O3—Cs1—O5	73.53 (14)	Cs2—O11—Ti2	109.4 (3)
O3—Cs1—O6	91.22 (16)	Ti1—O11—Cs4	107.2 (4)
O3—Cs1—O7	50.37 (14)	Ti1—O11—Ti2	144.8 (3)
O3—Cs1—O8	146.2 (2)	Cs4—O11—Ti2	105.5 (4)
O11—Cs1—O12	102.44 (17)	Cs1—O12—Ti2	98.5 (2)
O11—Cs1—O5	52.66 (13)	Cs1—O12—Cs3	7.05 (15)
O11—Cs1—O6	129.24 (16)	Cs1—O12—Cs2	75.37 (15)
O11—Cs1—O7	73.45 (14)	Cs1—O12—Ti1	120.1 (2)
O11—Cs1—O8	48.55 (13)	Cs1—O12—Cs4	76.1 (3)
O12—Cs1—O5	97.92 (15)	Ti2—O12—Cs3	103.0 (3)
O12—Cs1—O6	128.31 (16)	Ti2—O12—Cs2	96.3 (2)
O12—Cs1—O7	50.33 (13)	Ti2—O12—Ti1	141.3 (3)
O12—Cs1—O8	90.75 (18)	Ti2—O12—Cs4	99.4 (3)
O5—Cs1—O6	112.97 (17)	Cs3—O12—Cs2	69.7 (2)
O5—Cs1—O7	47.64 (13)	Cs3—O12—Ti1	115.8 (3)
O5—Cs1—O8	100.72 (16)	Cs3—O12—Cs4	70.2 (4)
O6—Cs1—O7	138.15 (16)	Cs2—O12—Ti1	96.7 (2)
O6—Cs1—O8	120.66 (17)	Cs2—O12—Cs4	3.3 (3)
O7—Cs1—O8	100.73 (17)	Ti1—O12—Cs4	93.5 (3)
O4—Cs2—O11	55.21 (17)	Cs1—O5—Ti1	101.96 (18)
O4—Cs2—O7	129.1 (2)	Cs1—O5—As2	104.7 (2)
O4—Cs2—O2	141.4 (2)	Cs1—O5—Cs3	1.0 (2)
O4—Cs2—O8	143.0 (2)	Cs1—O5—Cs2	81.26 (17)
O4—Cs2—O3	118.93 (17)	Cs1—O5—Cs4	76.5 (4)
O4—Cs2—O12	95.55 (16)	Ti1—O5—As2	132.5 (3)
O4—Cs2—O1^i	125.6 (2)	Ti1—O5—Cs3	102.7 (3)
O4—Cs2—O5	92.46 (17)	Ti1—O5—Cs2	98.1 (2)
O11—Cs2—O7	88.21 (18)	Ti1—O5—Cs4	99.9 (3)
O11—Cs2—O2	146.8 (2)	As2—O5—Cs3	104.5 (3)
O11—Cs2—O8	89.55 (18)	As2—O5—Cs2	124.2 (2)
O11—Cs2—O3	100.82 (17)	As2—O5—Cs4	124.1 (4)
O11—Cs2—O12	52.13 (14)	Cs3—O5—Cs2	80.6 (3)
O11—Cs2—O1^i	155.6 (2)	Cs3—O5—Cs4	75.8 (4)
O11—Cs2—O5	143.29 (19)	Cs2—O5—Cs4	4.8 (3)
O7—Cs2—O2	88.89 (17)	Cs1—O6—Cs3	5.80 (16)
O7—Cs2—O8	49.87 (14)	Cs1—O6—As2	127.8 (2)
O7—Cs2—O3	100.09 (17)	Cs1—O6—Ti1	97.14 (19)
O7—Cs2—O12	84.30 (16)	Cs3—O6—As2	127.1 (3)
O7—Cs2—O1^i	73.73 (19)	Cs3—O6—Ti1	97.2 (3)
O7—Cs2—O5	128.30 (18)	As2—O6—Ti1	134.9 (3)
O2—Cs2—O8	63.91 (17)	Cs1—O7—Cs2	90.85 (16)
O2—Cs2—O3	47.36 (14)	Cs1—O7—Ti2	87.38 (17)
O2—Cs2—O12	94.68 (18)	Cs1—O7—As2	95.5 (2)
O2—Cs2—O1^i	51.20 (15)	Cs1—O7—Cs4	87.4 (3)
O2—Cs2—O5	52.18 (15)	Cs2—O7—Ti2	135.4 (3)
O8—Cs2—O3	51.03 (14)	Cs2—O7—As2	96.0 (2)
O8—Cs2—O12	48.94 (14)	Cs2—O7—Cs4	4.9 (3)
O8—Cs2—O1^i	91.02 (18)	Ti2—O7—As2	128.5 (3)
O8—Cs2—O5	115.6 (2)	Ti2—O7—Cs4	131.7 (4)
O3—Cs2—O12	50.88 (14)	As2—O7—Cs4	99.7 (4)
O3—Cs2—O1^i	98.42 (17)	Cs1—O8—Cs3	7.12 (15)
O3—Cs2—O5	78.64 (16)	Cs1—O8—Ti2	113.9 (2)
O12—Cs2—O1^i	138.6 (2)	Cs1—O8—Cs2	100.6 (2)
O12—Cs2—O5	125.7 (2)	Cs1—O8—As2	108.9 (2)
O1^i—Cs2—O5	55.82 (17)	Cs1—O8—Cs4	101.0 (3)
O1—Ti1—O11	84.0 (2)	Cs3—O8—Ti2	120.3 (3)
O1—Ti1—O5	81.4 (2)	Cs3—O8—Cs2	95.7 (3)
O1—Ti1—O2	83.0 (2)	Cs3—O8—As2	103.6 (3)
O1—Ti1—O6	85.4 (2)	Cs3—O8—Cs4	96.0 (4)
O1—Ti1—O12	172.7 (2)	Ti2—O8—Cs2	100.7 (2)
O11—Ti1—O5	94.9 (2)	Ti2—O8—As2	133.8 (3)
O11—Ti1—O2	166.4 (2)	Ti2—O8—Cs4	102.9 (3)
O11—Ti1—O6	87.6 (2)	Cs2—O8—As2	87.6 (2)
O11—Ti1—O12	97.9 (2)	Cs2—O8—Cs4	2.8 (3)
O5—Ti1—O2	87.0 (2)	As2—O8—Cs4	84.9 (3)
O5—Ti1—O6	166.2 (2)	Cs1—Cs3—O2	90 (2)
O5—Ti1—O12	91.4 (2)	Cs1—Cs3—O3	74 (2)
O2—Ti1—O6	87.4 (2)	Cs1—Cs3—O12	90 (2)
O2—Ti1—O12	95.6 (2)	Cs1—Cs3—O5	9 (2)
O6—Ti1—O12	101.8 (2)	Cs1—Cs3—O6	114 (2)
O3—Ti2—O12	86.3 (2)	Cs1—Cs3—O8	84 (2)
O3—Ti2—O7	86.9 (2)	O2—Cs3—O3	136.2 (5)
O3—Ti2—O4^i	173.8 (2)	O2—Cs3—O12	165.2 (6)
O3—Ti2—O11	92.1 (2)	O2—Cs3—O5	91.5 (3)
O3—Ti2—O8	90.4 (2)	O2—Cs3—O6	56.1 (3)
O12—Ti2—O7	86.0 (2)	O2—Cs3—O8	74.5 (3)
O12—Ti2—O4^i	87.5 (2)	O3—Cs3—O12	57.6 (3)
O12—Ti2—O11	177.3 (2)	O3—Cs3—O5	67.3 (2)
O12—Ti2—O8	84.1 (2)	O3—Cs3—O6	93.1 (4)
O7—Ti2—O4^i	92.6 (2)	O3—Cs3—O8	140.6 (5)
O7—Ti2—O11	96.1 (2)	O12—Cs3—O5	90.9 (3)
O7—Ti2—O8	169.9 (2)	O12—Cs3—O6	136.3 (4)
O4^i—Ti2—O11	94.1 (2)	O12—Cs3—O8	90.8 (4)
O4^i—Ti2—O8	89.1 (2)	O5—Cs3—O6	108.0 (4)
O11—Ti2—O8	93.8 (2)	O5—Cs3—O8	92.6 (3)
O1—As1—O2	108.6 (3)	O6—Cs3—O8	125.9 (4)
O1—As1—O3	110.6 (3)	Cs2—Cs4—O4	126 (4)
O1—As1—O4	110.7 (3)	Cs2—Cs4—O11	98 (4)
O2—As1—O3	105.1 (3)	Cs2—Cs4—O7	84 (4)
O2—As1—O4	109.6 (3)	Cs2—Cs4—O2	41 (3)
O3—As1—O4	112.0 (2)	Cs2—Cs4—O8	38 (3)
O5—As2—O7	106.8 (3)	Cs2—Cs4—O3	11 (3)
O5—As2—O6	115.4 (3)	Cs2—Cs4—O12	48 (3)
O5—As2—O8	109.5 (3)	Cs2—Cs4—O1^i	88 (4)
O7—As2—O6	110.8 (2)	Cs2—Cs4—O5	79 (4)
O7—As2—O8	104.4 (3)	O4—Cs4—O11	57.4 (3)
O6—As2—O8	109.4 (3)	O4—Cs4—O7	135.2 (6)
Cs1—O1—Ti1	96.8 (2)	O4—Cs4—O2	139.5 (6)
Cs1—O1—As1	84.7 (2)	O4—Cs4—O8	140.6 (6)
Cs1—O1—Cs2	81.12 (17)	O4—Cs4—O3	115.7 (5)
Cs1—O1—Cs4	76.9 (4)	O4—Cs4—O12	95.0 (4)
Ti1—O1—As1	133.1 (4)	O4—Cs4—O1^i	132.3 (6)
Ti1—O1—Cs2	104.5 (2)	O4—Cs4—O5	94.8 (5)
Ti1—O1—Cs4	107.9 (4)	O11—Cs4—O7	88.8 (5)
As1—O1—Cs2	121.9 (3)	O11—Cs4—O2	138.9 (6)
As1—O1—Cs4	117.9 (5)	O11—Cs4—O8	86.5 (4)
Cs2—O1—Cs4	5.2 (4)	O11—Cs4—O3	96.1 (5)
Cs1—O2—As1	104.4 (3)	O11—Cs4—O12	50.5 (3)
Cs1—O2—Cs3	7.37 (16)	O11—Cs4—O1^i	160.7 (7)
Cs1—O2—Ti1	117.4 (3)	O11—Cs4—O5	143.8 (6)
Cs1—O2—Cs2	101.5 (2)	O7—Cs4—O2	85.2 (4)
Cs1—O2—Cs4	102.2 (3)	O7—Cs4—O8	47.7 (3)
As1—O2—Cs3	111.4 (3)	O7—Cs4—O3	94.4 (4)
As1—O2—Ti1	132.1 (4)	O7—Cs4—O12	81.2 (4)
As1—O2—Cs2	101.2 (3)	O7—Cs4—O1^i	73.5 (4)
As1—O2—Cs4	103.8 (4)	O7—Cs4—O5	126.2 (5)
Cs3—O2—Ti1	111.8 (3)	O2—Cs4—O8	59.9 (3)
Cs3—O2—Cs2	97.4 (3)	O2—Cs4—O3	44.2 (2)
Cs3—O2—Cs4	97.8 (4)	O2—Cs4—O12	88.4 (4)
Ti1—O2—Cs2	92.76 (19)	O2—Cs4—O1^i	48.8 (3)
Ti1—O2—Cs4	89.9 (3)	O2—Cs4—O5	49.9 (3)
Cs2—O2—Cs4	2.9 (3)	O8—Cs4—O3	47.5 (3)
Cs1—O3—Ti2	102.8 (2)	O8—Cs4—O12	46.2 (3)
Cs1—O3—Cs3	6.99 (17)	O8—Cs4—O1^i	87.0 (4)
Cs1—O3—As1	127.5 (3)	O8—Cs4—O5	109.1 (5)
Cs1—O3—Cs2	76.18 (14)	O3—Cs4—O12	47.6 (3)
Cs1—O3—Cs4	75.5 (3)	O3—Cs4—O1^i	92.9 (5)
Ti2—O3—Cs3	104.2 (3)	O3—Cs4—O5	74.2 (4)
Ti2—O3—As1	129.3 (3)	O12—Cs4—O1^i	131.0 (6)
Ti2—O3—Cs2	96.89 (19)	O12—Cs4—O5	118.9 (5)
Ti2—O3—Cs4	97.4 (3)	O1^i—Cs4—O5	55.4 (3)
Cs3—O3—As1	126.5 (4)

Symmetry code: (i) x+1/2, −y+1/2, z.

(III)

Crystal data

CsTiOAsO4	F(000) = 1200
Mr = 335.7	Dx = 4.517 Mg m^−3
Orthorhombic, Pna21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2c -2n	Cell parameters from 6293 reflections
a = 13.4623 (1) Å	θ = 3.0–45.4°
b = 6.8484 (1) Å	µ = 15.58 mm^−1
c = 10.7075 (1) Å	T = 183 K
V = 987.18 (2) Å^3	Rectangular, colourless
Z = 8	0.03 × 0.02 × 0.02 mm

Data collection

Siemens SMART CCD diffractometer	6940 independent reflections
Radiation source: fine-focus sealed tube	4282 reflections with F^2 > 2σ(F^2)
Graphite monochromator	Rint = 0.087
ω scans	θmax = 45.4°, θmin = 3.0°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −26→25
Tmin = 0.65, Tmax = 0.75	k = −13→13
30621 measured reflections	l = −16→21

Refinement

Refinement on F	1/σ^2
Least-squares matrix: full	(Δ/σ)max = 0.008
R[F^2 > 2σ(F^2)] = 0.043	Δρmax = 2.54 e Å^−3
wR(F^2) = 0.03	Δρmin = −2.69 e Å^−3
S = 1.88	Extinction correction: Zachariasen (1968), Eq22 p292 "Cryst. Comp." Munksgaard 1970
4282 reflections	Extinction coefficient: 473 (26)
144 parameters	Absolute structure: Flack (1983)
0 restraints	Absolute structure parameter: 0.06 (2)
0 constraints

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Cs1	0.61358 (4)	0.21495 (6)	0.3742 (4)	0.0124 (2)
Cs2	0.88981 (4)	0.30429 (6)	0.1165 (4)	0.0096 (2)
Ti1	0.62756 (8)	0.4964 (2)	0.0263 (4)	0.0041 (5)
Ti2	0.74947 (11)	0.73307 (17)	0.2770 (4)	0.0038 (5)
As1	0.49933 (6)	0.67332 (9)	0.2828 (4)	0.0035 (2)
As2	0.82191 (5)	0.49766 (12)	0.5375 (4)	0.0039 (2)
O1	0.5144 (5)	0.5217 (9)	0.1631 (6)	0.008 (3)
O2	0.4859 (5)	0.5408 (9)	0.4147 (6)	0.008 (3)
O3	0.6030 (4)	0.8078 (7)	0.3074 (6)	0.006 (2)
O4	0.3986 (5)	0.8164 (7)	0.2619 (6)	0.008 (2)
O11	0.7170 (4)	0.5572 (7)	0.1660 (6)	0.006 (2)
O12	0.7832 (5)	0.9431 (8)	0.4166 (5)	0.006 (1)
O5	0.8880 (5)	0.6978 (7)	0.5742 (6)	0.008 (2)
O6	0.8898 (4)	0.2982 (7)	0.5021 (6)	0.008 (2)
O7	0.7460 (4)	0.4527 (8)	0.6607 (5)	0.007 (2)
O8	0.7442 (5)	0.5490 (8)	0.417 (1)	0.009 (1)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cs1	0.0103 (3)	0.00564 (17)	0.0214 (3)	0.00157 (16)	−0.0031 (2)	−0.00195 (18)
Cs2	0.0063 (2)	0.00729 (16)	0.0152 (2)	0.00166 (16)	−0.0009 (2)	−0.00199 (18)
Ti1	0.0041 (5)	0.0054 (4)	0.0029 (5)	−0.0000 (5)	0.0003 (4)	−0.0003 (4)
Ti2	0.0042 (5)	0.0036 (4)	0.0036 (5)	−0.0007 (4)	−0.0004 (5)	−0.0002 (5)
As1	0.0034 (3)	0.0038 (2)	0.0032 (3)	0.0002 (3)	−0.0000 (3)	0.0001 (2)
As2	0.0042 (3)	0.0035 (2)	0.0039 (2)	−0.0003 (3)	0.0001 (3)	0.0003 (2)
O1	0.005 (3)	0.010 (2)	0.009 (3)	−0.000 (2)	0.0004 (18)	−0.0030 (18)
O2	0.008 (3)	0.009 (2)	0.007 (3)	0.002 (2)	0.0011 (18)	0.0044 (17)
O3	0.002 (2)	0.007 (2)	0.010 (3)	−0.001 (2)	0.0000 (18)	−0.0003 (18)
O4	0.008 (3)	0.004 (2)	0.012 (3)	0.000 (2)	−0.004 (2)	0.0003 (18)
O11	0.006 (2)	0.004 (2)	0.009 (2)	0.0008 (18)	0.0008 (19)	−0.0000 (16)
O12	0.006 (1)	0.006 (1)	0.006 (1)	0	0	0
O5	0.013 (3)	0.0039 (19)	0.007 (2)	−0.003 (2)	−0.002 (2)	−0.0009 (17)
O6	0.007 (2)	0.005 (2)	0.012 (3)	−0.001 (2)	0.003 (2)	−0.0003 (18)
O7	0.007 (3)	0.010 (2)	0.005 (2)	0.003 (2)	−0.0006 (18)	0.0029 (17)
O8	0.009 (1)	0.009 (1)	0.009 (1)	0	0	0

Geometric parameters (Å, º)

Cs1—O1	3.362 (7)	Ti1—O11	1.964 (7)
Cs1—O2	2.850 (6)	Ti1—O5	2.119 (5)
Cs1—O3	2.882 (5)	Ti1—O2	1.955 (7)
Cs1—O11	3.521 (6)	Ti1—O6	2.096 (5)
Cs1—O12	2.9813 (8)	Ti1—O12	1.719 (3)
Cs1—O5	3.214 (8)	Ti2—O3	2.063 (6)
Cs1—O6	3.310 (6)	Ti2—O12	2.124 (3)
Cs1—O7	3.468 (6)	Ti2—O7	1.953 (6)
Cs1—O8	2.9224 (8)	Ti2—O4^i	2.042 (6)
Cs2—O4	3.031 (6)	Ti2—O11	1.748 (6)
Cs2—O11	2.949 (6)	Ti2—O8	1.963 (3)
Cs2—O7	3.060 (5)	As1—O1	1.662 (7)
Cs2—O2	3.275 (7)	As1—O2	1.689 (7)
Cs2—O8	3.296 (2)	As1—O3	1.693 (5)
Cs2—O3	3.312 (8)	As1—O4	1.688 (6)
Cs2—O12	3.304 (2)	As2—O5	1.681 (6)
Cs2—O1^i	2.837 (6)	As2—O7	1.697 (6)
Cs2—O5	3.025 (6)	As2—O6	1.687 (6)
Ti1—O1	2.120 (7)	As2—O8	1.695 (3)
O1—Cs1—O2	51.22 (17)	O3—Ti2—O7	86.5 (2)
O1—Cs1—O3	114.7 (2)	O3—Ti2—O8	90.2 (2)
O1—Cs1—O12	142.81 (15)	O3—Ti2—O4^i	173.3 (3)
O1—Cs1—O5	49.33 (15)	O3—Ti2—O11	92.2 (3)
O1—Cs1—O6	86.20 (15)	O12—Ti2—O7	85.45 (17)
O1—Cs1—O7	95.56 (17)	O12—Ti2—O8	84.48 (15)
O1—Cs1—O8	81.72 (11)	O12—Ti2—O4^i	87.56 (18)
O2—Cs1—O3	139.94 (17)	O12—Ti2—O11	177.4 (2)
O2—Cs1—O12	158.10 (17)	O7—Ti2—O8	169.6 (2)
O2—Cs1—O5	100.18 (18)	O7—Ti2—O4^i	92.7 (3)
O2—Cs1—O6	53.80 (16)	O7—Ti2—O11	96.0 (3)
O2—Cs1—O7	146.6 (2)	O8—Ti2—O4^i	89.37 (19)
O2—Cs1—O8	74.12 (13)	O8—Ti2—O11	93.9 (2)
O3—Cs1—O5	73.51 (17)	O4^i—Ti2—O11	94.5 (3)
O3—Cs1—O6	91.79 (14)	O1—As1—O2	108.8 (3)
O3—Cs1—O7	50.38 (15)	O1—As1—O3	111.0 (3)
O3—Cs1—O8	145.71 (11)	O1—As1—O4	111.0 (4)
O12—Cs1—O5	97.73 (13)	O2—As1—O3	104.5 (3)
O12—Cs1—O6	128.12 (13)	O2—As1—O4	109.7 (3)
O12—Cs1—O7	50.16 (10)	O3—As1—O4	111.6 (3)
O12—Cs1—O8	90.20 (3)	O5—As2—O7	106.6 (3)
O5—Cs1—O6	113.96 (17)	O5—As2—O6	115.2 (3)
O5—Cs1—O7	47.62 (15)	O5—As2—O8	109.6 (2)
O5—Cs1—O8	100.98 (13)	O7—As2—O6	110.7 (3)
O6—Cs1—O7	138.99 (14)	O7—As2—O8	104.9 (2)
O6—Cs1—O8	120.26 (12)	O6—As2—O8	109.4 (3)
O7—Cs1—O8	100.45 (10)	Cs1—O1—Ti1	97.4 (2)
O3—Cs2—O4	120.40 (16)	Cs1—O1—As1	85.4 (3)
O3—Cs2—O11	101.44 (17)	Cs1—O1—Cs2	82.02 (16)
O3—Cs2—O12	51.02 (11)	Ti1—O1—As1	132.2 (4)
O3—Cs2—O2	47.90 (15)	Ti1—O1—Cs2	103.8 (2)
O3—Cs2—O8	51.17 (10)	As1—O1—Cs2	123.7 (3)
O3—Cs2—O1	99.44 (18)	Cs1—O2—As1	103.2 (3)
O3—Cs2—O5	79.71 (17)	Cs1—O2—Cs2	102.9 (2)
O3—Cs2—O7	100.23 (16)	Cs1—O2—Ti1	117.5 (3)
O4—Cs2—O11	55.60 (16)	As1—O2—Cs2	101.6 (3)
O4—Cs2—O12	96.52 (12)	As1—O2—Ti1	131.7 (4)
O4—Cs2—O2	142.30 (16)	Cs2—O2—Ti1	93.9 (2)
O4—Cs2—O8	143.94 (12)	Cs1—O3—Cs2	75.96 (16)
O4—Cs2—O1	124.1 (2)	Cs1—O3—Ti2	103.4 (2)
O4—Cs2—O5	92.43 (16)	Cs1—O3—As1	127.3 (3)
O4—Cs2—O7	128.20 (19)	Cs2—O3—Ti2	97.4 (2)
O11—Cs2—O2	147.7 (2)	Cs2—O3—As1	100.1 (3)
O11—Cs2—O8	89.75 (12)	Ti2—O3—As1	129.0 (3)
O11—Cs2—O1	153.8 (2)	Cs2—O4—As1	126.6 (3)
O11—Cs2—O5	144.08 (14)	Cs2—O4—Ti2	98.3 (2)
O11—Cs2—O7	87.88 (15)	As1—O4—Ti2	133.1 (3)
O12—Cs2—O2	95.25 (15)	Cs2—O11—Ti1	102.8 (2)
O12—Cs2—O8	49.25 (4)	Cs2—O11—Ti2	109.2 (3)
O12—Cs2—O1	139.24 (16)	Ti1—O11—Ti2	144.8 (3)
O12—Cs2—O5	126.98 (16)	Cs1—O12—Cs2	74.82 (6)
O12—Cs2—O7	84.57 (11)	Cs1—O12—Ti2	98.72 (7)
O2—Cs2—O8	63.93 (13)	Cs1—O12—Ti1	120.45 (7)
O2—Cs2—O1	51.69 (17)	Cs2—O12—Ti2	96.32 (8)
O2—Cs2—O5	52.66 (16)	Cs2—O12—Ti1	96.37 (11)
O2—Cs2—O7	88.49 (16)	Ti2—O12—Ti1	140.74 (7)
O8—Cs2—O1	91.15 (13)	Cs1—O5—Ti1	101.9 (2)
O8—Cs2—O5	116.23 (14)	Cs1—O5—As2	105.1 (3)
O8—Cs2—O7	49.87 (11)	Cs1—O5—Cs2	81.79 (17)
O1—Cs2—O5	55.81 (16)	Ti1—O5—As2	132.7 (4)
O1—Cs2—O7	72.95 (17)	Ti1—O5—Cs2	98.0 (2)
O5—Cs2—O7	127.60 (14)	As2—O5—Cs2	123.7 (3)
O1—Ti1—O5	80.8 (3)	Cs1—O6—As2	127.5 (3)
O1—Ti1—O2	82.6 (3)	Cs1—O6—Ti1	97.2 (2)
O1—Ti1—O6	85.7 (2)	As2—O6—Ti1	135.2 (4)
O1—Ti1—O11	84.1 (3)	Cs1—O7—Ti2	87.8 (2)
O1—Ti1—O12	172.44 (18)	Cs1—O7—As2	95.2 (2)
O5—Ti1—O2	86.8 (3)	Cs1—O7—Cs2	91.14 (14)
O5—Ti1—O6	166.1 (3)	Ti2—O7—As2	128.1 (3)
O5—Ti1—O11	94.6 (3)	Ti2—O7—Cs2	136.3 (3)
O5—Ti1—O12	91.72 (19)	As2—O7—Cs2	95.6 (2)
O2—Ti1—O6	88.0 (3)	Cs1—O8—Cs2	100.82 (5)
O2—Ti1—O11	166.2 (3)	Cs1—O8—Ti2	113.79 (9)
O2—Ti1—O12	95.8 (3)	Cs1—O8—As2	109.20 (6)
O6—Ti1—O11	87.3 (2)	Cs2—O8—Ti2	100.03 (8)
O6—Ti1—O12	101.7 (2)	Cs2—O8—As2	87.50 (9)
O11—Ti1—O12	97.89 (18)	Ti2—O8—As2	133.83 (7)
O3—Ti2—O12	85.73 (19)

Symmetry code: (i) x+1/2, −y+1/2, z.