Tetragonal lattice parameters

F — ferromagnetic A — antiferromagnetic P — paramagnetic imp — impurity phase SR — spin reorientation Tq — Curie temperature Tn — Ndel temperature a and c — tetragonal lattice parameters, z — coordinate of B with c as its unit. 

Based on the present study. b Lattice parameter data from Ref. (54). c Pseudo-tetragonal lattice parameters. d Lattice parameter data from Ref. (25). Rest of the lattice parameter data from Ref. (35, 36). 

Fig. 1 Tetragonal lattice parameters as a function of onset Tc (ac susceptibility) for solid solution system (Lao.9(Ba,Sr,Ca)o.i)2Cu04 Indices attached to each data point express the ratio of alkaline earth ion compositions in the order of Ba, Sr and Ca e.g. [013] represents (Lao.9Sro.025Ca0.075)2Cu04 Reproduced with permission from Ref. 14. Copyright 1987, The Chemical Society of Japan.

Fig. 4 Variations of tetragonal lattice parameters ag and cq and Tc for the solid solution systems of (Lao.85Lno.05 r0.l)2 u 4 with different lanthanide ions. Reproduced with permission from Ref. 17. Copyright 1987, Publication Board, Japanese Journal of Applied Physics.

FIGURE 4 Low-temperature dependencies of the lattice parameters of (pseudo)-tetragonal (T), monoclinic (M), orthorhombic (O), and rhombohedral (Rh) PrAlOj phases, obtained on cooling and heating (solid and open symbols, respectively). The lines are guides for the eye. For the LT-V phase below 110 K, both monoclinic and tetragonal lattice parameters are shown (Vasylechko, unpublished data). 

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). 

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