Liquid crystal composition

A liquid crystal composition comprising:

• a first component consisting of at least one member selected from the group of compounds expressed by general formula (I-a), (I-b) or (I-c):
• ##STR35## wherein R.sup.1 represents an alkyl group of 1 to 10 carbon atoms, a second component consisting of at least one member selected from the group of compounds expressed by general formula (II-a), (II-b) or (II-c):
• ##STR36## wherein R.sup.2 represents an alkyl group of 1 to 10 carbon atoms or an alkenyl group of 2 to 10 carbon atoms in each of which groups one or two non-adjacent methylene groups may be replaced by an oxygen atom;
• Z.sup.1 represents --CH.sub.2 CH.sub.2 --, --COO-- or a single bond;
• Q.sup.1 represents H or F;
• A.sup.1 represents trans-1,4-cyclohexylene, 1,4-phenylene or trans-1,3-dioxan-2,5-diyl;
• A.sup.2 represents trans-1,4-cyclohexylene or 1,4-phenylene;
• and 1 represents 0 or 1, and
• a third component consisting of at least one member selected from the group of compounds expressed by general formula (III) or (IV):
• ##STR37## wherein, in formula (III), R.sup.3 and R.sup.4 each independently represent an alkyl group of 1 to 10 carbon atoms or an alkenyl group of 2 to 8 carbon atoms in each of which groups one or two non-adjacent methylene groups may be replaced by an oxygen atom;
• B and C each independently represent trans-1,4-cyclohexylene or 1,4-phenylene;
• Z.sup.2 represents --C.tbd.C--, --COO--, --CH.sub.2 CH.sub.2 -- or a single bond;
• and in formula (IV), R.sup.5 represents an alkyl group of 1 to 10 carbon atoms or an alkenyl group of 2 to 10 carbon atoms in each of which groups one or two non-adjacent methylene groups may be replaced by an oxygen atom;
• R.sup.6 represents an alkyl group, an alkoxy group or an alkoxymethyl group each of 1 to 10 carbon atoms;
• D represents trans-1,4-cyclohexylene or 1,4-phenylene in which a hydrogen atom on either 2- or 3-position may be replaced by F;
• E represents trans-1,4-cyclohexylene or 1,4-phenylene;
• Z.sup.3 represents --CH.sub.2 CH.sub.2 --, --COO-- or a single bond;
• and Z.sup.4 represents --C.tbd.C--, --COO-- or a single bond.