This plugin allows to set additional meta tags for SEO and other purposes in core Joomla! extensions.
Just download as this or install form url https://github.com/joomplace/extendedmeta/archive/master.zip
Go to "Extensions > Plugins" and search for Extended metadata. Enable it.
That's it. You can set page title different than the article title, and also can have control on other (in future) meta tags in "Create/Edit Article" page.