TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The phosphate crystalline particles contain positive ion having valence of 4 or 5. The positive ion is titanium ion (Ti4+) or zirconium ion (Zr4+). The amount of phosphate crystalline particle is 20-90 wt.%. The phosphate crystalline particles and polymer of methacrylic acid ester containing phosphoric acid group are crosslinked through phosphoric acid, metal alkoxide or soluble metal salt.    TECHNOLOGY FOCUS - POLYMERS - Preferred Component: The polymer of (meth)acrylic acid ester containing phosphoric acid group is polymer obtained by polymerizing ester derivative of formula (A).R11 = H or methyl;R12 = H, methyl or CH2Cl;n = 1-10. EXAMPLE - 70% zirconium n-propoxide (in g) (100) and propanol (100) were stirred. Distilled water (50) was added to the propanol solution. The resulting solution was further stirred for 3 hours, and the solvent was removed at 50degreesC. The obtained gel was dried at 100degreesC for 12 hours, to obtain zirconium oxide power (28). The obtained powder was added to the liquid mixture of 2M phosphoric acid (500 ml) and 1M hydrofluoric acid (100 ml), and stirred for 3 days at 50degreesC. The powder was collected from the resulting mixture, rinsed 2 times with distilled water and dried at 50degreesC for 10 hours. The dried product was pulverized, to obtain white powder (alpha-Zr(HPO4)2.H2O crystal) (45). The obtained powder was added to a liquid mixture containing acid-phosphoxy-polypropylene glycol-methacrylate (5) and methyl ethyl ketone (10). The resulting mixture was stirred at 80degreesC for 5 hours under nitrogen atmosphere. 2% methyl ethyl ketone solution of azobisisobutyronitrile (5) was dropped into the stirred solution. The resulting solution was maintained at 80degreesC and further stirred to obtain polymer solution. The obtained polymer solution was developed on Teflon, dried under reduced pressure at normal temperature for 24 hours and heat processed at 120degreesC for 2 hours to obtain a film having thickness of 0.12 mm. The obtained film had electroconductivity of 1.1x10-3 Scm-1.