Abstract: An object of present invention is to provide a compound or a salt thereof constituting lipid particles that can achieve a high nucleic acid encapsulation rate and excellent delivery of nucleic acids, and to provide lipid particles and pharmaceutical composition using the compound or a salt thereof, which can achieve a high nucleic acid encapsulation rate and excellent delivery of nucleic acids. According to an aspect of the present invention, a compound represented by Formula (1) or a salt thereof is provided. In the formula, each symbol has a meaning defined in the present specification.

Abstract: A composition comprising Ba and Sr salts of carboxylic acids represented by the formula: C.sub.n H.sub.2n+1 COOH wherein 3.ltoreq.n.ltoreq.7, and having structures represented by the following formula (I): ##STR1## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 each represent a hydrogen atom, a methyl group or an ethyl group, and M represents Ba or Sr, can be used to form thin films of Ba.sub.1-x Sr.sub.x Ti.sub.y O.sub.3. A composition comprising a barium carboxylate, a strontium carboxylate and a titanium alkoxide in a mixed solvent of a carboxylic acid and an ester, can also be used to form Ba.sub.1-x Sr.sub.x Ti.sub.y O.sub.3 thin films. The proportion of the mixed solvent is 2-11 molar times as much as the Ti. A composition comprising salts of carboxylic acids represented by R.sup.a COOH wherein R.sup.a is a linear or branched alkyl group having 3-7 carbon atoms, as the Ba and Sr sources, and Ti(OR.sup.b).sub.4 wherein R.sup.