TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preparation (claimed): Compound (I) is prepared by high-energy ball milling method, fused salt reaction method, solvothermal reaction method, or solid phase reaction method. Preferred Method: The high-energy ball milling involves weighing raw materials according to stoichiometric ratio of compound (I) including carbonate, nitrate or hydroxide of (rubidium, potassium, sodium, lithium, or silver), oxide or nitrates of rare-earth element (Re), and elemental titanium oxide or chloride; adding raw materials into special tank container; adding stearic acid, n-amyl alcohol or deionized water and ethanol; high-energy ball milling at 100-400 revolutions per minute for 1-100 hours, with reversing mode milling at intermittent interval of 10-200 minutes and 5-60 minutes, respectively, in which stearic acid is added at 0-300% amount of mixture and n-amyl alcohol is added at 1-50% amount of mixture; diluting milled material with ethanol; centrifuging; separating pretreated powder; heat treating at 500-1000 degrees C for 1-10 hours; and cooling to obtain compound (I). It preferably involves adding 1-200 wt.% (preferably 10-100 wt.%) stearic acid and 1-100 wt.% (preferably 5-100 wt.%) n-amyl alcohol; high-energy ball milling at 150-380 revolutions per minute for 2-50 hours (preferably at 300-380 revolutions per minute for 2-20 hours) , with reversing mode milling at intermittent interval of 20-100 minutes and 10-60 minutes (preferably 30 minutes and 20 minutes); diluting with ethanol; standing for 10-30 minutes (preferably 20 minutes); centrifuging; separating powder; and heat treating powder at 500-1000 degrees C for 1-8 hours (preferably 2-8 hours). The fused salt reaction method involves weighing raw materials according to stoichiometric ratio of compound (I) including chlorides of (rubidium, potassium, sodium, lithium, or silver), oxide, sulfates, nitrates, or chloride of rare-earth element (Re), and elemental titanium oxide; adding starting material of titanium into chlorides of (rubidium, potassium, sodium, lithium, or silver) as molten salt; controlling chlorides of (rubidium, potassium, sodium, lithium, or silver) at mass ratio of (1:0.5);(1:5); milling and mixing raw materials in agate mortar for 1-5 hours to prepare molten salt reaction precursor powders; transferring precursor powders into corundum crucible; heat treating at 700-1050 degrees C for 1-10 hours; cooling after precursor is converted into temperature-sensitive luminescent material; soaking resulting precursor into warm deionized water at 50-90 degrees C for 1-100 hours; continuously changing water for several times; washing remove excess (rubidium, potassium, sodium, lithium, or silver) chloride; filtering; and drying solid at 100-150 degrees C to obtain compound (I). It preferably involves controlling chlorides of (rubidium, potassium, sodium, lithium, or silver) at mass ratio of (1:1);(1:2) (preferably (1:1.5)-(1:2)); milling and mixing raw materials in agate mortar for 2-3 hours preferably 2 hours to prepare molten salt reaction precursor powders; transferring precursor powders into corundum crucible; heat treating at 720-990 degrees C for 2-4 hours (preferably at 730-990 degrees C for 4 hours); cooling after precursor is converted into temperature-sensitive luminescent material; and soaking resulting precursor into warm deionized water at 60-80 degrees C for 10-72 hours (preferably at 60-80 degrees C for 24-72 hours). The solvothermal reaction method involves taking raw materials according to stoichiometric ratio of compound (I) including hydroxides of (rubidium, potassium, sodium, lithium, or silver), nitrate or chloride of rare-earth element (Re), titanium elemental selected from titanium tetrachloride, titanium tetra-n-butoxide (tetrabutyl titanate) or titanium tetraisopropoxide, solvent selected deionized water, ethanol or ethylene glycol; adding starting material with deionized water, ethanol, or ethylene glycol; stirring to fully dissolve; controlling (rubidium, potassium, sodium, lithium, or silver) hydroxide and titanium molar ratio at (5:1)-(15:1); transferring solution to hydrothermal axe for solvent thermal reaction at 120-250 degrees C for 2-40 hours; diluting milled material mixture with ethanol; centrifuging; removing pretreated powder; heat treating powder at 500-1000 degrees C for 1-10 hours; and cooling to obtain compound (I). It preferably involves controlling (rubidium, potassium, sodium, lithium, or silver) hydroxide and titanium molar ratio at (1:1)-(15:1); transferring solution to hydrothermal axe for solvent thermal reaction at 180-230 degrees C for 12-36 hours; diluting milled material mixture with ethanol; centrifuging; removing pretreated powder; and heat treating powder at 600-980 degrees C for 1-10 hours. The solid phase reaction method involves weighing raw materials according to stoichiometric ratio of compound (I) including carbonate of (rubidium, potassium, sodium, lithium, or silver), oxide, nitrates, or chloride of rare-earth element (Re), and titanium element selected from titanium dioxide (rutile, anatase or brookite); mixing starting material while controlling (rubidium, potassium, sodium, lithium, or silver) volatile excess of 1-10 wt.%; putting raw materials in mortar; grinding; adding alcohol and mixing for 2-5 hours; calcining milled material mixture at 700-1000 degrees C for 1-10 hours; cooling; adding calcined powder with ethanol; grinding for 2-5 hours; calcining at 800-1200 degrees C for 1-10 hours; and cooling to obtain compound (I). It preferably involves mixing starting material while controlling (rubidium, potassium, sodium, lithium, or silver) volatile excess of 1-5 wt.%; putting raw materials in mortar; grinding; adding alcohol and mixing for 2-3 hours; calcining milled material mixture at 800-950 degrees C for 4-6 hours; cooling; adding calcined powder with ethanol; grinding for 2-3 hours; and calcining at 900-1100 degrees C for 4-10 hours. The preparation of ceramic material preferably involves adding 2-10% polyvinyl alcohol as binder; stirring to dissolve; drying; granulating; screening through 60-160 meshes sieve to obtain spherical particles; pressing spherical particles to obtain green body with certain thickness and diameter; heat treating green body in muffle furnace at 500-600 degrees C for 10 hours; and sintering at 950-1350 degrees C for 2-8 hours.