An orthorhombic polymorph of lanthanum ultraphosphate, LaP5O14, was firstly synthesized by the high temperature solid-state reaction and structurally characterized by single-crystal X-ray diffraction technique. It crystallizes in the orthorhombic Pmna space group with a=13.155（3）, b=8.816（2）, c=9.115（2） , V=1057.1（4） 3 and Z=4. The structure features （P5O14）3-anionic ribbons linked with neighboring LaO8 polyhedra. The title solid-state compound is an insulator. Theoretically calculated energy band structure, density of states （DOS）, and optical response function by density function theory （DFT） for LaP5O14 were also performed.
The potassium terbium polyphosphate crystal KTb（PO3）4 has been synthesized using a high temperature solution reaction method. The structure and composition were characterized by single-crystal X-ray diffraction, powder X-ray diffraction and elemental analysis. The compound crystallizes in the monoclinic space group P21/n with a=10.3182（6）, b=8.9129（5）, c=10.7940（6） , β=105.993（1）o, V=954.3 3, Z=4, Mr=513.91, Dc=3.577 g/cm3, μ=8.585 mm（-1）, F（000）=960, S=0.955,（Δρ）max=1.380,（Δρ）min=–3.428 e/3, the final R=0.0301 and w R=0.0400 for 2301 observed reflections with I 〉 2σ（I）. In addition, pure powder of isostructural Rb Tb（PO3）4 was synthesized in order to investigate the optical property. Photoluminescence measurements show that both crystals ATb（PO3）4（A=K（1）, Rb（2）） are promising candidates to become solid-state visible green light-emitting sources.
