Supporting information

Transcription

1 Supportng nformaton S1. Sample characterzaton S1.1. Hall coeffcent and resstvty measurements Hall and resstvty measurements on sample B have been performed wth a PPMS (Physcal Property Measurement System) from Quantum Desgn n the range K. A bar of mm x mm x 0.63 mm was obtaned from the ngot of sample B. The Au wres used for the resstvty measurement were placed 3.45 mm apart centered around the mddle along the length of the sample. The Hall coeffcent was calculated accordng to: RR HH = EE HH jjjj = VV HHAA IIIIII where E H s the Hall feld, B s the magnetc feld, V H s the Hall potental, jj = II/AA s the current densty.e. the current dvded by the sample cross secton, and ll s the separaton of the transverse voltage leads. The carrer concentraton at 77 K was estmated through: 1 pp 77KK = RR HH,77K ee The same apparatus was used for electrcal resstvty measurements. S1.2. X-Ray dffracton Fgure S1 Reconstructon of the (0kl) plane, sample A, at 300 K wth enlargement on the (022) reflecton (1) and on the (002) reflecton (2) usng an n-house Bruker II dffractometer.

2 Fgure S2 Reconstructon of the (0kl) plane, sample B, at 300 K wth enlargement on the (020) reflecton (1), on the (022) reflecton (2) and on the (002) reflecton (3) usng an n-house Bruker II dffractometer. 2

3 Fgure S3 Reconstructon of the (0.5kl) plane, sample A, at 300 K usng an n-house Bruker II dffractometer. Fgure S4 Reconstructon of the (0.5kl) plane, sample B, at 300 K usng an n-house Bruker II dffractometer. 3

4 Sngle crystal X-ray data collectons on sample A and sample B were carred out at BL02B1, SPrng8 usng ω-scans. For sample A frames were collected wth Δω = 15 and one frame wth Δω = 5 at T = 20 K, 200 K, 300 K, 400 K. Addtonally 2 frames wth Δω = 15 were collected at 50 K, 75 K, 110 K. For sample B 10 frames wth Δω=15 and 3 frames wth Δω = 5 were collected at 20 K, 50 K, 80 K, 110 K, 200 K, 300 K. The data have been merged n Sortav. Refnements have been carred out n Jana2006 n whch: ( obs) F ( calc) F R obs = F ; GOF = w ( obs) ( F ( obs) F ( calc) ) n p ( F ( obs) F ( calc) ) w wrobs = w F 4 ( obs) 2 ; Table S1 Expermental detals (sample A, sngle crystal) Crystal system Space group Z λ (Å) Μ (mm -1 ) Crystal sze (equvalent radus) (μm) (snθ/λ) max cubc Fm3 m (Å -1 ) Temperature (K) Emprcal Formula Formula weght Sn Te Sn 0.977Te Sn Te Sn Te Sn Te Sn Te Sn Te

5 (g mol -1 ) F a (Å) (8) 6.282(2) (17) (18) (10) 6.314(1) (11) V (Å 3 ) ρ, g cm N measured N measured (I>3σ) N unque N unque (I>3σ) Average redundancy Completeness % R 1=R merge R obs (I>3σ) wr obs (I>3σ) GOF (I>3σ) Δρ (e Å -3 ) (I>3σ) Δρ (e Å -3 ) (I>3σ) weght scheme appled -3.0 / / / / / / / / / / / / / / 0.2 5

6 Table S2 Expermental detals (sample B, sngle crystal) Crystal system Space group cubc Fm3 m Z 4 λ (Å) Μ (mm -1 ) 7.3 Crystal sze (equvalent radus) (μm) 25 (snθ/λ) max (Å -1 ) 1.0 Temperature (K) Emprcal Formula Formula weght (g mol -1 ) Sn 0.973Te Sn 0.978Te Sn Te Sn Te Sn Te Sn Te F a (Å) (16) (18) 6.295(2) 6.300(2) 6.312(2) 6.327(2) V (Å 3 ) ρ, g cm N measured N measured (I>3σ) N unque N unque (I>3σ) Average redundancy Completeness % R 1=R merge R obs (I>3σ) wr obs (I>3σ) GOF (I>3σ) Δρ (e Å -3 ) (I>3σ) -2.1/ / / / / /1.9 6

7 Δρ (e Å -3 ) (I>3σ) weght scheme appled -0.8/ / / / / /1.3 Table S3 Extncton correcton parameters as derved from Jana2006, harmonc model. Sample A, 20 K Type 1, Lorentzan G ISO = ± Type 1, Gaussan G ISO = ± Type 2 RHO ISO = ± Sample B, 20 K Type 1, Lorentzan G ISO = ± Type 1, Gaussan G ISO = ± Type 2 RHO ISO = ± Conventonal PXRD data were collected from 300 to 800 K on a Rgaku Smartlab equpped wth a copper source. The measurements were executed n a closed system under Argon. S1.3. Dfferental thermal analyss (DTA) DTA analyss has been performed wth a Netsch STA 449 C Jupter from 30 C to 650 C and back to 30 C at a heatng rate of 10 C/mn under Argon flux. The DTA curve shows a large broad partally rreversble exothermc transton. A small knk s vsble at 233 C whch can be attrbuted to meltng of metallc Sn whch s present as a tny mpurty n the PXRD pattern. 7

8 Fgure S5 DTA curve from 30 C to 650 C (red curve) and from 650 C to 30 C (blue curve). A broad exothermc transton appears at around 150 C and contnues for all the range of temperature consdered. The small endothermc knk at 233 C s due meltng of the Sn mpurty. 8

9 S2. Results and dscussons S2.1. Cell parameters Table S4 Thermal expanson wth temperature for sample A and B (sngle crystal data) Sample A T (K) a (Å) (8) (2) (17) (18) (10) (10) (11) Sample B (sngle crystal data from 20 to 300 K, conventonal PXRD data from 320 to 800 K) T (K) a (Å) (16) (18) (2) (2) (2) (2) (5) (5) (3) (4) (4) 9

10 (4) (4) (4) (4) (4) (5) (5) (4) (3) (3) (4) (4) (1) (4) (5) (7) (6) (6) (6) (7) 10

11 S2.2. Harmonc model Table S5 Isotropc ADPs and ste occupancy factor of Sn from the harmonc model Sample A T (K) U so Sn (Å 2 ) U so Te (Å 2 ) Occupancy(Sn) R 1 R obs wr obs (7) (6) (8) (16) (14) 0.977(2) (11) (9) (12) (10) (8) (12) (6) (5) (8) (6) (5) (8) (5) (4) (7) Sample B T (K) U so Sn (Å 2 ) U so Te (Å 2 ) Occupancy(Sn) R 1 R obs wr obs (2) (2) 0.973(2) (2) (19) 0.978(2) (2) (18) (18) (19) (16) (12) (19) (17) (12) (18) (16) (16)

12 S2.3. Anharmonc model Table S6 Gram Charler coeffcents and ste occupancy factor of Sn. Te s refned harmoncally. Sample A T (K) D 1111 Sn (Å 4 ) D 1122 Sn (Å 4 ) Occupancy(Sn) (3) (9) 0.980(9) (9) (5) 0.980(3) (6) (3) (14) (9) (4) (15) (5) (19) (10) (6) (3) (10) (9) (4) (9) Sample B T (K) D 1111 Sn (Å 4 ) D 1122 Sn (Å 4 ) Occupancy(Sn) (16) (7) 0.980(2) (15) (6) 0.984(2) (12) (5) (19) (15) (6) 0.986(2) (17) (8) (13) (2) (9) (18) 12

13 13

14 Fgure S6 Nuclear probablty densty functons for sample B n the anharmonc model wth both Sn and Te refned through Gram-Charler coeffcents. Both Sn and Te have been translated n the (0,0) poston. The plane of the map s the (001). The values have been normalzed to 1 and the contour are plot as (2 n )/A where 1 n 8 and A s the unnormalzed value of maxmum of nuclear densty. An addtonal contour has been added at 0.99 n the normalzed scale to show the nuclear poston. Despte the large correlatons t s ndcatve to notce evdent non-sphercal features, especally for the Te atom. At 200 K the Te nuclear maxma are not n the hgh symmetry poston. Fgure S7 Nuclear probablty densty functons for sample B at 200 K n the anharmonc model wth Te refned through Gram-Charler coeffcents whle keepng Sn harmonc. The maps have been plotted wth the same settngs as Fgure S2. 14

15 Fgure S8 Nuclear probablty densty functons for sample A n the anharmonc model wth both Sn and Te refned wth Gram-Charler coeffcents. The maps have been plotted wth the same settngs as Fgure S2. No devatons from sphercty are seen for Sn and Te. 15

16 S3.4 Maxmum entropy method Fgure S9 MEM electron densty maps of Sn (left) and Te (rght) n the (001) plane from 20 to 400 K for sample A. Contour values have been set to [64, 128, 256, 512, 1024, 2048] eå

17 Fgure S10 Fourer dfference (F obs-f MEM) maps n the (100) plane at dfferent temperatures for sample A. The values have been normalzed between Δρ max and Δρ mn. Fgure S11 Fourer dfference (F obs-f NXMEM) maps at dfferent temperatures for sample A. The values have been normalzed between Δρ max and Δρ mn 17

18 Fgure S12 MEM electron densty maps of Sn (left) and Te (rght) n the (001) plane from 20 to 300 K for sample B. Contour values have been set to [64, 128, 256, 512, 1024, 2048] eå

19 Fgure S13 Fourer dfference (F obs-f MEM) maps at dfferent temperatures for sample B. The values have been normalzed between Δρ max and Δρ mn. 19

20 Fgure S14 Fourer dfference (F obs-f NXMEM) maps at dfferent temperatures for sample B. The values have been normalzed between Δρ max and Δρ mn. 20

21 Fgure S15 Integral breadth β (deg), (y axs) as functon of Temperature (K). The low order reflectons show a slght broadenng approachng 10 K. (002) and (004) should not splt or broaden f a phase transton Fm3 m R3m occurs. At hgh 2θ values the broadenng appears neglgble. 21

22 Fgure S16 Comparson of low order reflectons at 10 and 150 K. Fgure S17 Comparson of hgh order reflectons at 10 and 150 K. 22