The database on structural phase transitions is presented in the simple and easy accessible form of table. The symmetry changes and temperature for 3446 phase transitions and the references for each of 2242 registered crystalline materials with well defined stoichoimetry are the main data in this table. The rules for constructing and reading the database table are also presented.

Structural phase transitions in crystals. I. Database

Lattice parameters of LiKSO4 have been measured in the temperature range 155–300 K with an X-ray single-crystal Bond diffractometer. Below 180 K LiKSO4 transforms on cooling into an orthorhombic phase. Above this temperature there is a broad range of an intermediate hexagonal phase which depends on the real structure of the sample and differs considerably on cooling and on heating. The anomalies in the physical properties of LiKSO4 reported in the literature have been explained. The crystal structure of the low-temperature and intermediate phase, as well as the mechanism of the phase transitions, are suggested and discussed.

X-ray study of the low-temperature phase transitions in LiKSO4

Unusual sequence of commensurate-incommensurate phase transitions observed in KLiSO4

Optical studies of ferroelastic phase transition and domain structures in K3Na(SeO4)2 crystals

The piezoelectric and elastic properties of LiKSO4 crystals, grown from aqueous solutions at 315 K, were studied in the temperature range from 100 up to 300 K by means of the dynamical series impedance method and by the low-frequency torsion pendulum technique. The parameters studied were found to exhibit anomalous temperature dependence. This suggests ferroelastic properties of LiKSO4 crystals in the temperature range below 190 K.

Anomalous changes in the piezoelectric and elastic properties of LiKSO4 crystals

The pyro- and dielectric properties of LiKSO4 crystals, grown at 315 K by the dynamical method in isothermal conditions, were studied from 100 up to 300 K. The properties studied were found to exhibit anomalous temperature-dependent variations.

Anomalous changes in the pyroelectric and dielectric properties of LiKSO4 crystals

Optical studies of LiKSO4 crystals were performed in polarized 11yh.t within the temperature range from 300 up to 1000 K. The observations confirmed the existence of two phase transitions at about 700 and 940 K respectively. The high-temperature phase between 700 and 940 K was found to be ferroelastic.

High temperature ferroelastic phase in LiKSO4 crystals

The temperature dependence of dielectric permittivities, shear moduli and internal friction of LiCsSO4 crystals were measured Large anomalies were found in G1 and G2 shear moduli and in the internal friction Q-1 for the samples in a and b directions, near the Curie point Tc = 202 K The temperature dependence of stress-strain hysteresis loops was also studied In the samples cut out along the a direction a single loop was found while in the b direction a double hysteresis loop was observed

Ferroelastic properties of LiCsSO4 crystals

Pyrbelectric, dielectric and thermal properties of LiRbS (SO4)3 -1. 5H2SO4 were studied in the temperature range from 100 to 400 K. At 137 K marked anomalous changes in pyroelectric and thermal properties were observed, Below 137 K ferroelastic domain structure was found to appear.

T. Krajewski

Papers

Anomalous changes in the pyroelectric and dielectric properties of LiKSO4 crystals

Anomalous changes in the piezoelectric and elastic properties of LiKSO4 crystals

High temperature ferroelastic phase in LiKSO4 crystals

Ferroelastic properties of LiCsSO4 crystals

Pyroelectric, dielectric and thermal properties of LiRbS (SO4)3 1.5HzSO4 crystal in the temperature range from 100 to 400 K