Tetragonal 4mm

Dielectric properties Thermal expansion coefficient Pyroelectric properties 

---

Lithium tetraborate (LBO) crystals are grown by Czochralski or Bridgman technique (Gualtieri et al. 1992). Crystal belongs to the tetragonal 4mm symmetry class (i.e. see Shi-Ji Fan 1993). As a consequence of the symmetry, crystal is... 

Lead titanate exhibits only one stmctural phase transition from paraelectric cubic mhm to ferroelectric tetragonal 4mm phase. Curie temperature is relatively high 490° C. Lead titanate has the biggest anisotropy in the tetragonal lattice parameter ratio c/a = 1.06 among all perovskite crystals. Due to the anisotropy it exhibits relatively high hydrostatic piezoelectric coefficient dh (higher than PZT ceramics). 

Knowledge of the diffraction symmetry of a crystal is useful for its classification. If the Laue group is observed to be 4/mmm, the crystal system is tetragonal, the crystal class must be chosen from 422,4mm, 42m, and 4/mmm, and the space group is one of those associated with these four crystallographic point groups. 

At temperatures below Tc BaTi03 belongs to the tetragonal crystal class (symmetry group 4mm) it is optically uniaxial, and the optic axis is the x3 axis (nQ = 2.416, ne = 2.364). When an electric field is applied in an arbitrary direction the representation quadric for the relative impermeability is perturbed to... 

What are the nonzero piezoelectric coefficients for a single domain of the ferroelectric tetragonal phase of PZT (class 4mm) ... 

Reactions of In metal with alkyl halides RX (X = Br or I R = Me, Et, Pr", or Bu") generally gave pure R3ln2X3, which were characterized spectroscopically. The crystal structure of Me2lnBr, tetragonal, space group /4mm, reveals the presence, for the first time in the solid state, of a linear dimethylindium ion, Me2ln The two In—C distances are not exactly equal [2.116(6) and 2.226(7)... 

---